Centrifugal pipe casting apparatus



June 19, 19-34. N, F. s. RUSSELL ET AL 1,963,149

CENTRIFUGAL PIPE CASTING APPARATUS Filed June 6, 1933 Jwuewtou [1 6:fiwssell ?Mrman Eek/2M dimge 3 w .l M I My Patented June 19, 1934963,149 CENTRIFUGAL PIPE CASTING APPARATUS Norman F. 8. Russell andFrederick G; Langenhm Edlewater Park,

N. 1., asslgnors to United States Pipe and Foundry Company, Burlington,N. 1., a corporation of New Jersey Application June 6, 1933, Serial No.674,505

2 Claims.

Our invention relates to pipe casting apparatus of the type in which arotatable pipe mold having a cylindrical section is operatively combinedwith a retractable dumping trough for 5 molten metal which can beinserted in and withdrawn from the mold and which, when in operativeposition in the mold, is adapted to deliver its charge of molten metalalong the entire length of the cylindrical portion of'the mold and theobject of our, invention is to provide suitable means whereby thecylindrical surface of the pipe mold may be progressively coated withfinely divided dry coating material in advance of the pouring of moltenmetal from the dump trough in contact with said coated surface. a

In our application filed October 19, 1932, Serial Number 638,480, wehave described the method of coating the cylindrical surface of a pipemold with finely divided dry coating material by means of a charged jetof a carrier-gas charged with such coating material and directed againstthe cylindrical surface of the mold so as to build up thereupon acoating which as applied consists not only in the particles of finelydivided dry coating material but also of adsorbed films of gassurrounding the particles of coating material and particularly we havedescribed in our said prior application a method in which thecylindrical portion of the pipe mold is progressively charged withmolten metal through a relatively retractable runner delivering themolten metal to the rotating mold in the form of a helix and in which ajet of carrier gas is progressively directed against successive areas ofthe mold shortly before the so coated portions of the mold are contactedby the molten metal issuing from the run- I ner, the jet of carrier gasbeing progressively retracted through the cylindrical portion of themold at substantially the same rate of retraction as that of the runnerthrough which the molten metal is delivered and we have pointed out inour said application the importance of contacting the coated surface ofthe mold with molten metal as promptly as possible after the deposit ofthe coating upon the mold and the importance of so regulating .thesupply of finely divided dry coating material delivered by the jet as toform a coating not substantially thicker than that the desiredretardation in heat transfer from the molten metal to the mold; such aretardation, for example, as would prevent the formation of areas ofchili upon the outer surfaceof. the casting. The avoidance of anexcessive use of coating material and consequent excessivethickthicizncss which is found effective to bring about.

ness of the coating is important not only as affooting. the structure ofthe casting but also because we have found it to be truethatwith'increasing thickness of the coating there is increasedliability for portions of the coatin'g'to'be- 00 come displaced, thatis, to flake off or slip'in advance of the contact of molten metaloverthe coated surface and to be displaced by contact with the stream ofmolten metal fed to, the, mold.

While, for reasons that we havestated'it 'is 66 advisable that thethickness of the coating deposited upon the mold should be kept as thinas will make it effective to prevent the formation of a chill,particularly with regard tothe quality of the casting produced and'whileit is true that 10 thicker coatings are more liable to fracture than 1thinner coatings, we have found that in using the dump trough method ofcharging a coated mold with molten metal there is less tendency for theoccurrence of fractures and displacement of 15 the coating from theimpact of the molten metal than is the casewhere the molten metal issupplied through a retracting runner and that in such a method ofcasting it is practical to use a considerably thicker coating than wherethe metal is supplied through a retracting runner. The special objectwhich we have in view in our present invention isto provide an effectivemeans for coating the cylindrical portion ofa pipe mold with finelydivided dry coating material in .advance of the charging of molten metalinto the pipe mold from a dump trough delivering its charge of moltenmetal substantially simultaneously along the entire length of thecylindrical portion of the mold and our invention consists, 00 generallyspeakingiin combining with a centrifugal pipe mold and a relativelyretractable dump trough which is moved outward from the mold to becharged with molten metal and moved into the mold when chargedsc as toextend over the entire cylindrical portionv thereof and, when tilted,discharge its contents along the length of the cylindrical portion ofthe mold, a comparatively short jet noz'ale of a length in the directionof the axis of the mold which is only a fraction of. the length of thecylindrical portion of themold such jet nozzle being secured at the endoi-the dump trough and provided with means for'feeding to it a supply ofcarrier gas charged with finely divided dry coating material. It will beobvious that in an apparatus so constructed the jet nozzle moving in andout of the mold as the dump trough is inserted or retracted will beprogressively directed against all portions of the rotating pipe moldand that a Jet of charged carrier 11o gas issuing from the nozzle duringthe in or out movement of the dump trough will deposit upon the rotatingsurface of the mold a helical band of the coating material and that witha proper regulation of the speed of travel of the dump trough this bandwill be so laid down as to have over-lapping edges in adjacent coils soas to build up uponthe surface of the mold a substantially uniformcoating of the dry finely divided materialv with more or less permeationby the adsorbed films of carrier gas surrounding the particles ofcoating material.

As noted in our prior application, the volume and velocity of the jet ofcarrier gas issuing from the nozzle should be so regulated as to avoidthe impingement of the carrier gas against the surface of the mold withsufiicient energy to rement, the mold, housing and mixing chamber beingshown in longitudinal section, and

Figure 2 is a fragmentary isometric view of a portion of the apparatusshown in Fig. 1, on a larger scale.

A is the mold housing which may serve as a water box, B a centrifugalmold extending through the housing and rotatably supported on the endwalls of the housing, the mold having, as shown, a bell end B and acylindrical section indicated at B. C indicates a motor supported on thehousing and coupled to rotate the mold by gearing indicated at C Dindicates a core secured in place in the bell mouth of the mold. Eindicates a carriage movable longitudinally on tracks indicated at E inalignment with the mold. F indicates a dump trough for a molten metaladapted, when in operative position, as shown in Fig. 1', to extend overthe cylindrical portion of the mold and over an adjacent portion of thebell end. F indicates the pouring lip of the dump trough and 1 acylindrical ex tension from the end of the dump trough proper. This isrotatably supported in bearings E E secured to the carriage E. Findicates a lever handle for tipping the dump trough. G is acounter-weight extending rearwardly from the mold and adapted to balancethe weightof the charged dump trough. H indicates a conduit pipe foracarrier gas which is secured to the dump trough on the opposite sidefrom its pouring lip and which is connected, as shown, by a hose H withsuitable mechanism for supplying carrier gas and charging the carriergas with finely divided dry particles of the mold coating material. Asshown, we have indicated a mixing chamber or gun I, supplied withcarrier gas by means of a nozzle J, provided, as shown, with aregulating valve J and a gauge J and receiving gas under pressure from asource, not shown. K indicates the presenceof mechanism for feedingfinely divided dry coating material into the mixing chamber. As anysatisfactory feeding device can be used, we have not thought itnecessary to illustrate the particular construction of this part of themechanism which, so far as it is shown, is that forming the subjectmatter of the patent application filed by Hunt and Arnold, October 29,1932, Serial Number 640,258, new Patent No. 1,939,703., dated Dec. 19,1933. L innold, October 29, 1932, Serial Number 640,257.

In operation, the mold, after the securing of the core D in its place inthe bell end, is set in rotation and the carriage E having been retmtedso as to withdraw thedumping trough F from the mold, the dumping troughis charged with molten metal. The carrier gas is conducted to the mixingchamber I through the nozzle J and finely divided dry coating materialfed to the mixing chamber as by the feeding device indicated at K andthe charged carrier gas passes 'through the hose H and pipe H into andthrough the nozzle L. The carriage E is then moved toward the mold insuch manner that the dumping trough F will be projected into and throughthe cylindrical portion of the mold at a regulated rate of speed and sothat the jet of charged carrier gas will be projected against therotating cylindrical wall of the mold in such manner as to progressivelydeposit upon said wall a helical band of finely divided dry coatingmaterial with the edges of such helical band over-lapping adjacent coilsof the helix, thus building up upon the entire cylindrical surface ofthe mold a continuous coating made up of the particles of coatingmaterial and adsorbed films of the carrier gas surrounding saidparticles. The coating of the cylindrical portion of the mold will becompleted when the dump trough and supported nozzle reach the positionshown in Fig. 1 and as soon as this is effected the supply of carriergas is cut off as by means of the valve J so that no further chargeoffcarrier gas is fed to the nozzle L and the dump trough F is thentilted as by the lever l to feed its contents of molten metalsubstantially simultaneously along the entire length of the cylindricalportion of the coated rotating mold after which the dump trough isretracted from the mold, the core D removed from the bell end of themold and the cast pipe extracted and the apparatus operated, asdescribed, for the renewed coating of the mold and casting of a newpipe.

It is, of course, practicable to apply the coating to the mold inadvance of the pouring of molten metal by first inserting the dumptrough in the mold, as shown in Fig. 1, then turning on the supply ofcharged carrier gas and, as the jet of charged gas issues from thenozzle L, withdrawing the dump trough at a substantially uniform rate ofspeed so that the coating is applied to the mold progressively,beginning with the portion of the cylindrical section adjacent to thebell and ending with the spigot end of the mold, then turning off thesupply of charged carrier gas and re-inserting the dump trough, chargedwith molten metal, into the mold, as shown in Fig. 1, and then tiltingthe dump trough to feed its charge of molten metal to the coated surfaceof the mold, although such a method of procedure would involve anundesirable delay in the pouring of the metal after the coating isapplied.

The quantity of finely divided dry coating material delivered throughthe jet nozzle L during the coating of the mold should, for the bestresults, be so regulated as to build up a coating on the cylindricalportion of the mold not materially exceeding that thickness which willeffect such a retardation in the heat transfer from the molten metal tothe mold as is found desirable in practice; such a retardation, forexample, as will prevent the formation of what is known as a chill onthe outer surface of the casting and, as the eiiiciency of the coatingas a retarder of heat transfer diminishes to acertain extent if thecoated surface is not promptly covered by molten metal, due, no doubt,to the escape of some of the entrained carrier gas, the amount of finelydivided dry coating material to be delivered through the jet nozzle andthe consequent thickness of the coating as initially applied to the moldwill vary to a certain extent for the time interval lapsing between thecoating of the mold and the pouring of the metal upon the coated surfaceand it will be obvious that the metal should be poured as soon aspossible after the coating is applied to the mold but in all cases theapplication of the coating of materially greater thickness than thatfound to eiiect a desirable retardation of heat transfer should beavoided as with increased thickness in the coating there is greaterliability for portions of the coating to flake of! or become displacedand greater liability for portions of the coating to be displaced by theimpact the molten metal upon the coated surface.

- Having now described our invention, what we claim as new and desire tosecure by Letters Patent, is:

entire length of the cylindrical portion of the mold, a jet nozzle of alength in a direction .the axis of the mold which is a comparativelysmall fraction of thelength of the cylindrical portion of the moldadapted for the delivery of a jet of carrier gas charged with finelydivided dry -"coating material, said jet nozzle being supported by'thedump trough and located adjacent to the free end thereof, means forsupplying the Jet nozzle with a carrier gas charged with finely divideddry coating material and means for outting off the supply of chargedcarrier gas to the nozzle.

2. Apparatus as called for in claim 1,in which the nozzle is secured atthe end of a pipe attached to the side of the dump trough opposite toits pouring lip and forming a part 01' the means for supplying thenozzle with charged carrier gas.

NORMAN F, S. RUSSELL. FREDERICK C. LANGENBERG.

